Conventionally, there have been devices called projectors for projecting images on wall surfaces and screens. The most common projectors are known as stationary projectors, which receive power from a commercial power supply and are fixed to a certain position when they operate. Stationary projectors project, when they are fixed, an image on a fixed position on a wall surface or a screen. In contrast, portable projectors have been proposed recently that are small and easy to carry. In contrast to stationary projectors, for which there is an assumption that they will keep projecting an image on a fixed position, portable projectors can be carried around and have an advantage in that a position irradiated with an image is easily adjustable by manual operation.
A portable projector is described in the patent literature 1 that includes a projecting unit that projects an image including a predetermined shape pattern onto a projection surface, thereby creating a projection image of the image; an imaging unit that acquires a taken image of a subject; and a brightness adjusting unit that adjusts, based on the predetermined shape pattern included in the taken image of the projection image that is taken and acquired by the imaging unit, the brightness of the projection image.